Electrical connectors using spring action are known from, for example, U.S. Pat Nos. 3,453,587, 3,845,451, 3,828,301, 3,895,853 and 4,083,622 which are commonly assigned herewith and in which one of the present inventors is also named as an inventor.
These systems are used primarily for forming an electrical connection between two elements one of which can be a plug engaging the spring-like lamellae of such connectors.
Electrical terminals are known in a variety of configurations and for a variety of purposes and mention can be made of several for background purposes. For example, terminals may be used in so-called mosaic circuit configurations in which a number of components are removably interconnected by being plugged in or otherwise tied to terminals maintaining a connection between the components. In addition, such terminals may be used to tie a number of components or conductors to another conductor or component, in miniature electronic circuitry and in macrocircuitry for a variety of connecting purposes.
In general, a terminal can make an electrical connection between one conductor and another conductor and can have a plurality of contact pins, wires or the like which form the connection. The terminal can be of the screw type, can be of the spring or plug type, or can be of the twist type, depending on how the conductor or group of conductors is or are anchored to the terminal.
For breadboarding purposes, in the establishment of circuit designs or for the fabrication of prototype or other circuits, it is known to provide an insulating board with a multiplicity of such terminals, usually in a regular array, to which various electronic components can be connected, to which conductors such as jumpers between components may be connected, and to which printed circuit conductors may be electrically connected as required.
While the present invention will be described primarily in connection with such experimental tables or boards, more generally breadboards, it should be noted that the principles of the present invention are more generally applicable to any type of circuit arrangement in which a terminal for a plurality of conductors must be provided.
Referring again to experimental boards and particularly breadboards provided with a multiplicity of terminals in a regular array, mention may be made of the fact that each such terminal may be used to connect one or more pins, bars, tabs, tongues or other connective elements of an electrical component such as a resistor, condenser, diode or transistor, to a conductor, such as a jumper wire. The terminals are also used to mechanically anchor and/or electrically connect encapsulated circuit elements and the array of terminals should be designed such that the connecting relationship of the various components can be readily ascertained and understood so that the system may be used for educational and evaluation purposes as well as circuit design. The components which are interconnected by such terminals can be complete circuits capable of performing particular functions and provided with a limited number of conductors for, for example, connecting the circuit unit to a source of power and to input and output signal processing units. These circuit elements can be mechanically and electrically fitted into the terminals of the experimental table or plate and any breadboard carrying the terminals. The assembly may thus be suitable for the mechanical mounting and electrical connection of the circuit elements, for display of the circuit organization and the like.
Conventional electrical terminals for the aforementioned purposes consist of more or less complicated contact springs which generally are mounted between an upper plate and a lower plate of an experimental table and to which access is afforded by bores provided in the upper plate and serving to permit the contact pins, wires or conductor elements generally of the electronic components or units to engage the contact springs. The units are then electrically interconnected by these contact springs to one another.
The terminals are distributed more or less uniformly on the base or board formed from the upper and lower plates. The connecting bores associated with each contact spring are themselves generally regularly spaced and distributed. For example it is known to provide a cruciform arrangement of contact bores, e.g. at the corners of a rhombus, for each contact spring or to arrange the contact bores along a line, the contact spring being similarly cruciform in configuration or of linear configuration.
The conventional terminals have various disadvantages. For example, it is disadvantageous to require a respective connecting bore in the upper plate for each wire to be tied to a respective terminal and to arrange such bores in a perfectly regular configuration. Because of this characteristic of prior-art systems, the terminals of earlier systems have been able to accommodate only a reduced number of (generally up to four) components. Attempts to increase the number of interconnecting a plurality of terminals result in removing a number of intrinsically individual terminals and in making the circuit unsightly or incapable of satisfactory monitoring.
A further disadvantage, especially when the system is to be used for didactic purposes, is that a center of connection is not readily ascertainable for each terminal or group of connecting bores. The junctions appear to be diffuse and it is difficult to ascertain how a circuit can be improved using a conventional system with a distributed array of bores each for a single connector and all cooperating with a single terminal.
In addition, the conventional systems have been found to be relatively complicated to fabricate, to be expensive, and to require contacts or terminals of relatively complicated configuration.